THE THEORY OF JETS
63
hearth of this furnace is constantly covered with a layer of air,
and why the waste gases, as analyzed by M. Asseyew, showed
3.85 per cent of CCb and 16.65 per cent of 62- This was the
cause of the abandonment of these furnaces at the Alapayewsky
works.
The conclusion that the good or bad working qualities of plate-
heating furnaces depended upon the height of the working opening
was entirely unlocked for at this time. Since then this conclusion
has been completely verified. There is no doubt whatever that
this is only one of the numerous surprises which will be revealed
by the application of the hydraulic theory to furnaces,
X. THE APPLICATION TO HOT GASES OF THE THEORY OF JETS
OF WATER
If the resistance due to friction in the pipes and in the air is
neglected the vertical height to which a vertical jet of water will
rise will be equal to the head and will be
The jet from an
inclined fountain de-
scribes a parabola
whose middle ordi-
nate (Fig. 42) will be
Tr v2 sin2 5
FIG. 42.
In applying these formulas to hot gases, that is to say, to a
light liquid in motion within a heavy liquid, it is necessary to
turn the diagram upside down, as the particles in motion are acted
upon, not by their weight and gravity in a downward direction,
but by the difference between the weight of the particles in motion
and a corresponding volume of the medium within which their
motion takes place. The resultant force will act in an upward
direction, thus inverting the diagram, as is indicated in Fig. 43.
Yesmann has developed the following expression for an infin-
itely thin jet of hot gases, projected from the port of an open-
hearth furnace: